Kathleen, when you do the deck screw thing, first find the approximate center where the head will sit on the shelf, then with washer in place, drill down from top to get a point on the base, ehtn drill up until screw head just shows--set head in place and hit with yur hand on top--this should leav a mark on the wood--using a 12 penny nail, or a small drill bit, drill a pilot hole into the wood.
If you find you have any problems with the screw NOT drawing up into the cork a bit, just remove screw and using a 1" spade bit, drill down about a half inch. Then glue and screw head in place---i used to use contact cement on both surfaces-allowed to dry, then made the joint, then drew down a bit with the screw.
the screw method is just faster and does not inviolve drilling large holes into the head.
Don't forget to fill the screw hole in bottom with plastic wood, allow to dry, then sand and seal!!
By the way, with the tan cork, all you will need to do is slightly round the bottom to avoid chipping of the cork---Unless you plan on hollowing the material, it does not require a bottom board, just a keel.
Have fun.